{#分类导航的标题#}
<ul class="classes-box">
    {% for item in class_keys %}
        <li class="top-nav">
            <a href="/demo/nav/{{ item.name }}/" {% if now_cls == item.name %}
               style="background-color: blueviolet"
            {% endif %}>
                {{ item.name|capfirst }}
            </a>
        </li>
    {% endfor %}
</ul>